The invention relates to renovating pipeworks by utilizing a technique called lining, and to treating a renovation liner to be used in the renovation prior to renovating.
Pipes, for instance sewage pipes, may be renovated e.g. by coating the inner surface of a pipe with an appropriate coating material. One such coating material is a polyester sleeve impregnated with epoxy resin.
The polyester sleeve may be a covering called a “resizable liner” suitable for coating pipes having diameters of different thicknesses. The structure of the resizable liner is such that when necessary, it will stretch out to coat a pipe with a diameter thicker than the diameter of the liner normally (in a non-stretched state) is. Non-stretched, the diameter of the liner may be for instance 70 mm and, when stretched, 100 mm. Consequently, the same liner is suitable for coating the inner surface of both a 70 mm pipe and a 100 mm pipe.
The pipe assemblies to be coated may have joints at which a pipe having a thinner diameter is connected with a pipe having a thicker diameter. One such joint may, for instance, be provided in the sewage system of a residential building, e.g. a block of flats, wherein branch lines from the flats are provided with pipes with thin diameters, which are connected to a main line which has a thicker diameter. Presently, when coating such a joint, separate coating elements designed and dimensioned appropriately for the joint are used. These elements have turned out to be difficult to install in place such that the result meets the quality requirements set for the installation work. If a flaw occurs while installing an element and, for instance, the coating element sticks poorly to the joint, the element has to be removed from the joint for instance by grinding and subsequently replaced by a new coating element.
According to the prior art, it is also possible to coat the joint by utilizing a technique called overlap lining if both pipes of the pipe assembly are of the same thickness. In such a case, no separate coating element is necessary in the joint but the liner used for coating the branch line is extended by an appropriate length into the main line as well. When the coating liner has become attached to the branch and main lines once the epoxy resin has dried; the main line clogged by the coating liner is drilled open by an appropriate machining tool.
Finnish Patent No. 122524 discloses a method of treating a resizable liner. The document discloses a method of preparing a resizing sleeve for lining a jointing point of a pipe assembly comprising pipes of thicker and thinner diameter. The method comprises steps for stretching the diameter of the resizing sleeve to the diameter of the size of the thicker pipe of the pipe assembly, installing an installation hat according to the thicker pipe in diameter of the pipe assembly by airtightly gluing it onto the stretched resizing sleeve, and returning the resizing sleeve to the size of the thinner pipe in diameter of the pipe assembly to be lined.
A problem with the above-described arrangement is the physical size of the resizing sleeve treated, resulting from using in the installation hats and calibration sleeves fabric-base materials corresponding to the renovation liner. It prevents the method from being used for instance in a pipework which involves two resizing procedures in sequence or which is otherwise cramped for space. In addition, when renovating branch points, branch tees are necessary in order to make the branch tight.